How to Install a Roof Vent in Your Attic

Tackling Moisture in the Roof

When there is heat and moisture trapped in an attic it can cause damage to your roof. If there is insulation in the attic it can trap this moisture, creating mold and mildew inside the home. Installing a vent in the roof not only allows this moisture a way to escape, but also works to minimize the temperature difference between the air outside your home and the air inside your attic. This not only helps to prevent the moisture and mildew from forming, but cooling the attic can create energy savings for your home as well.

Since the size of the attic determines exactly how many roof vents you need, start by first getting the dimensions of your attic. To determine this measurement, calculate the square footage of the attic and multiply the length times the width. By using this number you can then estimate that you need approximately one for every 150 square feet of attic space.

Once you have determined how many you need to install, you will next mark the location of where each one will go. The simplest way to do this is to drive a long nail upwards through both the wood and the shingles while you are still in the attic. Begin by measuring 18-inches down from the peak of the roof. Place the nail in a central spot between the rafters, then drive the nail upward through the wood and shingles. This will allow you to locate the designated spot for each vent once you are on the roof.

Locate the designated area on the roof for the first one and make a circle with chalk to indicate the cutout area for the vent. Make the cutout area about ½-inch larger than the opening of the vent.

Use a utility knife to cut away the shingles as you follow the chalk line. Remove the cutaway pieces of shingle from your work area.

Use a drill to make a starter hole in the middle of the wood that is exposed from removing the shingles. This allows you to fit the blade of your jigsaw into the wood to cut out the square.

Push back the self-adhesive of the shingles remaining around the hole. Use a small crowbar or putty knife. Inspect the area for any roofing nails that might prevent the vent from fitting properly over the hole you have created.

Set the vent over the hole. The edges should be partially covered by the shingles that you initially pushed back. Secure the vent to the roof by hammering roofing nails into the lower edge. Check to ensure that it is securely in place.

Keep water from leaking in around the vent by applying roof cement to both the top of and also down at the sides where the shingles meet up to the vent. This helps to hold it in place. Apply a small amount of roof cement at the foot of the vent. This secures the lower portion to the shingles and also seal the holes you have made from the nails you drove into the wood. Repeat the process to install the remaining vents.